d cried:

"Where are you, Tom? Tell us, so we can get you out!"

They all listened, and faintly heard:

"I'm in some sort of an old vault, partly underground. It's below what
used to be the office. There's a flight of steps, but be careful, as
they're rotten."

Eagerly they looked around Mr. Damon saw a door in one corner of the
office, and tried to open it. It was locked, but a few blows from the
sledge smashed it, and then some steps were revealed.

Down these, using due caution, went Ned and the others, and at the
bottom they came upon another door. This was of sheet iron and was
fastened on the outside by a big padlock.

"Stand back!" cried Ned, as he swung the sledge, and with a few blows
broke the lock to pieces.

Then they pulled open the door, and into the light staggered Tom Swift,
a most woe-begone figure, and showing the effects of his imprisonment.
But he was safe and unharmed, though much disheveled from his attempts
to escape.

"Thank Heaven, you've come!" he murmured, as he clasped Ned's hand. "Is
the tank all right?"

"All right!" cried Ned. "And now tell us about yourself. How in the
world did you get here?"

"It's quite a yarn," answered Tom. "I've got to pull myself together
before I answer," and he sank wearily down on a step, looking very
haggard and worn.

Chapter XXIII

Gone

"Here, eat some of this," and Ned held something out to his chum.
"It'll bring you up quicker than anything else, except a cup of hot
tea, and we'll get that as soon as you can get away from here," went on
the young bank clerk.

"What is it?" Tom asked, and his voice was very weary.

"It's a mixture of chocolate and nuts," replied Ned. "It's a new form
of emergency ration issued to soldiers before they go over the top. Our
Y.M.C.A. is sending a lot to the boys from around here who are in
France. I was helping pack the boxes ready for shipment, and I kept out
some to show you. Lucky I had it with me. Eat it, and you'll feel a lot
better in a few minutes. You haven't had much to eat, have you?"

"Very little," answered Tom, as he nibbled half-heartedly at the
confection Ned gave him, while Mr. Damon went out to the automobile and
came back with a thermos bottle filled with cool water. He always
provided himself with this on taking an automobile trip.

Tom managed to eat some of the chocolate, and then took a drink of the
cool water. In a little while he declared that he felt better.

"Then co